Cloud computing is an emerging model of business computing. Computing tasks are distributed by the cloud computing in a resource pool composed of a large number of computers, and the resource pool is called “cloud”. Through the cloud computing, various application systems can obtain computing capability, storage space and a variety of software services as required.
“Cloud” is some virtual computing resources which can be maintained and managed by its own, and usually is some large-scale server clusters, including computing servers, storage servers, bandwidth resources, and so on. Cloud computing centralizes all the computing resources together, and realizes the automatic management by software without participation of human. It makes the application provider not worry about messy details, and be able to concentrate on their services, thus benefiting innovation and cost reduction.
The basic principle of cloud computing is, by making the computing distribute on a large number of distributed computers, rather than on local computers or remote servers, the running of an enterprise data center is more similar to that on Internet. It makes the enterprise be able to switch the resources to the applications which requires the resources, and access computers and storage systems as required. From the most fundamental sense, the cloud computing is an ability for using the software and data on the Internet.
It can be seen from the principle of the cloud computing that, the implementation of the cloud computing requires the large-scale server clusters to provide terminal users with the needed resources, such as the bandwidth, the storage space and the computing capability. Since the number of users having requirements and the level of the demand on the cloud computing are not evenly divided, they largely relate to the status of scientific research and local economy and. Therefore, allocating and placing the server clusters reasonably have a very important significance for improving the efficiency of cloud computing and allocating reasonably the cloud computing resources; however, there is no mechanism for configuring reasonably a cloud computing network at present.